Loud speaker



Dec. 18,1928. V Y 1,695,779

A. NYMAN 'oUD SPEAKER Filed Nov. 24, 1925 ATTORNEY Patented Dec. 18, 1928.

f jfuNi-LTED STATES;

l MALEXANDER NYMAN, OF NEW YORIL N.'Y.

LOUD, SPEAKER.

Applicationizled November 24, 1925. ySerial No. 71,246,

My Vinvention relates to improvements soundreproducing devices; particularly electromagnetically operated loud speakers.

,An object of this invention is to provide a 45l loud speaker adapted for use with radio receivingsets; capableof accurate adjustment and responsive to relatively weak currents;

and characterized by very greatvsensitiveness and high ellieiencyin operation.

@ther obj ects and advantages of my invention. Vwillbe made clear from the following description land the novel features ot' my improvements are defined in the appended claims. `Butl this disclosure is illustrative 15 only, and I may change the construction a'ctually shown, in all matters relating merely to shape, size and arrangement of parts, without` departing from the scope and spirit of the invention, as indicated by tliebroad 2o and general meanings ofthe terms in which the appendedclaims are expressed.

On the drawings, .Y

Figure 1 is a side view partly in section of a loud speaker according to this invention;

Figure 2 is an end `view thereof;

Figure 3 is a side viewof the support in which the parts of the `loud speaker are mounted;

Figures 4,-5 and 6 show details; and

Figure 7 presents curves showing the mode of operation of my invention.

The same numerals identify the same parts throughout. l

In the detailed description of the structure shown, the numeral 1 indicates a vibratory diaphragm of metal or other suitable material, preferably corrugated; this diaphragm being connected to an armature 2 associated with an electromagnet 3, to cause movement 40 of same. The diaphragm is located in a casing 4, the bottom of which is dished or provided with arecess 5; and upon the casing is a cap or closure 6, secured by fastening means such as screws 7. The rim of the cap clamps the edge ofl the diaphragm against the edge of the casing, and in the recess 5 around the periphery thereof, may be an annular cushion, packing ring or gasket 8 against which the circumference of the diaphragm is firmly pressed. At the center of the cap is an outlet neck 9, to be connected to a trumpet or the like, to amplify the sound which the diaphragm creates.

the bot- From the outside' or lower face of tomoi the casing 4 rprojects a web 10, extending diametrically across the casing and being in the positions illustrated, the upper and lower edges ot the recess 1l are formed with notches 12 and 13, in line with each other, as inFigures 1 and The web is not ot' very great thickness, as indicated in Figure 2, and along its lower edge it has opposite lateral anges 14.

To cooperate with the electromagnet 3, I employ a permanent source of magetic ilux such as a pair of horse-shoe magnets 15; one disposed against each face` of the -web 10; the limbs of the magnets being as far apart as the width of the recess 11. These magnets or magnetic elements 15 are permanent magnets and are held in place by clamps 16, each magnet fitting more or less snugly between one oi' the flanges Hand the bottom of the y cap 4.

In the notch 12 and between the adjacent limbs of the magnets 15, I put a soft iron pole 17. This pole piece 17 is clamped in position by the magnets 15, and it has lugs 18 at its outer or lower end to serve as bearings for a pivot pin 19 carrying the armature 2. This armature has two flanges 2O pierced for the pin 19; and is connected at one end to a rod 21, which runs to the middle of the diaphragm 1, through an opening 22 in the web 10. The ends of the rod 21 are riveted to both diaphragm and armature.

In the other notch 13 I put the core of the In operation the coils of the magnet 3 are l joined to a radio receiving set, and upon signals arriving, the coil 3 will so affect the armature 2, as to rock it and vibrate the diaphragm 1. Normally, of course, the magnets 15 also attract the armature 2, the permanent magnetic flux acting through the *polepiece 17 and laminat-ions 23; but the armature is held motionless thereby and does not begin to move till impulses of current traverse the coil of the magnet 3.

For purposes of adjustment, the portions 27 and 28 of the web 10 at the entrance to the recess 11 are perforated at 29 and 30 respectively; the latter perforation being threaded. These perforatlonsreceive a threaded rod 31 having a screw head 32. When this rod is screwed in tight, it tends to draw the portions 27 and ,28, and the limbs of the' magnets toglether; thus regulating the distance between t e armature 2 and the poles of the magnet 3. l

.'By this construction I obtain a loud speaker which is very sensitive, and gives a maximum movement of the diaphragm for whatever degree of force is momentarily exerted on the armature 2. In other lwords, what is generally known as a balanced condition between the tension of the diaphragm, and the force dueto the magnets, is secured. For example,

)let the ab'scissas in Figure 7 represent the forces that'play a part in the operation of the diaphragm, and the ordinates represent the displacement or degree of movement of the diaphragm 1. Thus, it the line vA is the force due to the stresser tension of the diaphra m when moved or o erated, and the line -is the force due to t e magnetic flux which influences the diaphragm, this force being the resultant of the permanent magnetic flux-of te magnets 15 and the emporary ux dueto the impulses of current in the coil of the'magnet 3, serving as means to vary the total flux'; the force which actually causes the diaphragm to vibrate will beindicated by the line C, plotted by subtracting the abscissas for instantaneous values of B from ordinates of corresponding values of A. From the shape of the line or curve C, one can see that a small increment or decrement of the unbalanced force acting on the ,diaphragm can cause a relatively large movement of the latter. By means of the member 31, the loud speaker' can be adjusted with extreme neness and accuracy till the required operating' conditions are found.

It will be clear from the above that whereas heretofore the magnetic balance in this type of loud speaker was obtained in a hit or miss manner of adjusting the airgap a predetermined length to suit the strength of the magnet, I provide apositiveadjusting means for the alr gap. According to my invention a practical construction is obtained for securing the best possible magnetic balance on each manufactured unit of loud speakers.

Hence my improved loud speaker is very ecient and gives excellent results on even the weakest incoming oscillations.

Having described my invention, whaty I believe to be new and desire tosecure and protect by Letters Patent of the United States is 1.. A loud speaker comprising a sound roduclng surface, a rocking `armature connected thereto, asource of magnetic flux,

ymeans for providing additional magneticilux,

and a member under'tension for controlling the effect of said flux and said means in the actuation of said surface.

2. A loud speaker comprising a sound producing surface, a rocking armature connected thereto, `a source of magnetic flux, means comprising an electro-magnet to provide additional magnetic flux, and a controlling member nnder tension for said source and said means to adjust the operation of the loud speaker. l

3. A loud speaker including a sound producing surface, a rocking armature cdnnected thereto, a magnet to iniiuencethe armature, and a member under tension to adjust the rel'- ative positions of the magnet and the armature to control the operation of the loud speaker. fl. A loud speaker comprising a permanent magnet, an electromagnet with two adjacent poles of opposite polarity mounted thereon, a sound producing surface, a rocking armature connected to the surface and disposed adjacent said electromagnet, and a member .to adjust the relative positions of the two poles of the electromagnet and the opposite pole of the permanent magnet.

5. A loud speakercomprising a permanent magnet, an electromagnet with two adjacent poles of opposite polarity mounted thereon, a sound producing surface, a rocking armature' connected to said sound producing sur face, and disposed ladjacent to said electromagnet, a magnetic pole piece adjacent said armature, ,and a member to adjust the relative positions of said electromagnet and said ma eticpole piece and connected to draw sai electromagnet and said .pole piece to'- ward eachother. j

6. A loud speaker comprising a permanent magnet, an electromagnet with two adjacent poles of opposite polarity adjacent a pole thereof, a rocking' armature adjacent said electromagnet, a sound producing surface connected to the armature, and a member to control the distance between the limbs of the permanent magnet to regulate the operation of the loud speaker.

lllO

7. A loud speaker comprising a web havv ing a recess, a Vmagnet secured to the web with its limbs at the sides of the recess, a diaphragm, an armature connected to the diaphragm, and an adjusting member extending across said recess and operable to draw the limbs of the magnet towards each other.

8. A loud speaker comprising a webvhaving a recess, a magnet having its limbs laid along the sides of the recess, a diaphragm,

' an armature connected to the diaphragm, a

pole-piece adjacent one limb of the magnet,l an electromagnet adjacent the other limb, and an adjusting member acting to draw said limbs toward each other.

9. A loud speaker comprising a diaphragm, a casing therefor, the casing having a Web on its bottom, the web having a recess in one side and opposite flanges along its outer end, U-shaped magnets at each side of the web between the fianges and the casing, the limbs of the magnets extending along the sides of the recess, a polepiece set in a notch in the web between adjacent limbs of the permanent magnets, an electromagnet set in a similar notch in the web between the remaining limbs of said magnets, an armature between said electromagnet and said polepiece and connected to the diaphragm, and an adjusting device engaging the web across said recess to regulate the distance between the limbs of the permanent magnets.

10.` A loud speaker comprising two magnets, and a web between said magnets, the Web being shaped to receive a polepiece to cooperate with the magnets.

1].. A loud speaker comprising two magnets, a web between said magnets, the web being shaped to receive the core of an electromagnet and an armature to be-influencc by the electromagnet. l

12. A loud speaker comprising a web, having an open-ended recess, a magnet on each face of the web, the limbs of the magnets extending along the edges of said recess, said edges each having a notch therein, and a pole-piece in one of said notches and a core in the other between said magnets.

13. A loud speaker comprising a web having a recess, a magnet secured to the web with its limbs at the sides of the recess, a diaphragm, an armature connected to the diaphragm, and an adjusting member engaging the web and extending across said recess to regulate the effect of said ma et.

14.. A loud speaker comprising al web, a fixed magnet supported on said web, an electromagnet and cooperating-polepieces supported on said web and an armature in operative relation to said electromagnet.

15. A sound producing device comprising a supportin'g'web, one or more magnetic elements mounted thereon, an electromagnet supported on said web, and means for adjusting the magnetic action of said elements to secure magnetic balance.

16. A sound producing device comprising a supporting -web with magnetic elements mounted thereon, an electromagnet, a rocking armature and means for distorting said web to change the effect of said magnetic elements.

In testimony whereof I affix my signature.

ALEXANDER NYMAN.y 

